Information Technology Reference
In-Depth Information
Figure 1-6: From left to right: MultiMediaCard, RS-MultiMediaCard, MMCplus,
MMCmobile, and MMCmicro.
The MultiMediaCard specifications are a product of the MultiMediaCard
Association (MMCA) ( www.mmca.org) . The MMCA board consists of over
a dozen semiconductor and technology companies. The organization is ded-
icated to open, royalty-free standards.
The MultiMediaCard specifications are the ultimate authority on the physi-
cal interface and command set. Data sheets for specific MultiMediaCards
are another helpful source of information about the interface, protocols, and
card-specific information.
Packages
Table 1-2 compares the five MultiMediaCard variants. The cards are avail-
able in three form factors and with interfaces of 7, 10, and 13 pins (Figure
1-6). The original MultiMediaCard has a 7-pin interface and is about 1.25 x
1 inch in size. The RS-MultiMediaCard is functionally identical and about
half the size. The MMCplus TM and MMCmobile TM add 13-pin interfaces in
both form factors. The MMCmicro TM has 10 pins and is about half an inch
square.
Interfacing
A MultiMediaCard can use either of two synchronous serial interfaces: the
MultiMediaCard bus or SPI. Just about any microcontroller can implement
either bus. The MMCplus, MMCmobile, and MMCmicro can also use a
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